This invention relates to improvements in apparatus using a principle of electrolytic action to recover metal from a solution. It has particular advantage for use in recovering silver in a film processing installation and it will be so described, but only by way of illustration and not by way of limitation.
The X-ray departments of hospitals, for example, have extensive film processing operations. During the development of the films taken in such departments, silver freed from the film by the action of the applied X-rays is washed from the film by the fixer solution, of which it then becomes a part. As the silver content increases, the fixer solution tends to rapidly deteriorate and require early replacement. For this reason, as well as the potential value of the silver content, it is the practice to make an effort to extract the silver from the solution.
Systems used for the recovery of silver from a fixer solution as known in the prior art are relatively inefficient and the silver recovered thereby is often in a less than satisfactory condition. To the extent known, the prior art silver recovery systems require the use of a large motor and pump to draw the metal bearing solution from a fixing tank and deliver it to a separator wherein a rotatable spinner operates to induce a desired pattern of flow of the metal bearing fluid in a plating chamber, between an anode and a cathode. It has often been found in the use of this prior art apparatus that the silver extracted is relatively soft, a condition which does not insure that the silver will remain extracted from the solution during the separating cycle. Apart from this, in the operation of the rotating spinner heat is often produced to a degree that it upsets the chemical balance of the basic fixer solution in which the silver is embodied. This means that the fixer solution may not be reused.
Apart from the foregoing problems noted with reference to prior art systems and apparatus for recovering silver from a fixing solution, such prior art apparatus has been so constructed that when one desires to remove the silver which has been separated, fixer solution which is then in the separator may be lost. An additional problem found in use of the prior art separators of the type described is frequent malfunction due to deterioration of the electrical connections, particularly those required for energizing the anode and cathode.
Solution of all the noted problems was the objective of the efforts which resulted in the present invention.
Pursuant to Section 1.97 of Title 37 of the Code of Federal Regulations, as far as those substantively involved in the preparation of the present disclosure the most pertinent of the prior art publications is the U.S. Pat. No. 3,694,341. Another example of the prior art with which the invention is primarily concerned is found in U.S. Pat. No. 2,791,555.